Lakes are large bodies of water that form in natural cavities. Some are impenetrable rock valleys filled with streams, while others are filled with water rising from below. The more nutrients a plant has in a pond, the sooner it grows and turns into a marsh or swamp.

Flooded basins

Many lakes are formed from hard, impenetrable rocks by the moving ice of glaciers. Others occupy elongated craters in the earth’s crust or in volcanic craters. At one time many parts of the river were cut off from the mainstream, while some were once part of the sea.

Glacial Lake:- The lake is formed in a glacier cavity in the highlands of the Carpathian Mountains in Bulgaria.

Ebb and flow

Some ponds are like wet sponge cavities, filled with water at the bottom. As the groundwater level rises and falls, so does the lake. Some fill up quickly, then empty almost overnight. These lakes are most common in the limestone landscapes like Western Ireland below.

Kettle Lakes

In the early ice age, deep frozen regions are often filled with lakes. In this satellite image of the land near the Gulf of Ob in northern Russia are kettle lakes, ice cubes sinking into soft soil and then melting.

Lake water 

The cold water of the lake contains very few dissolved minerals that can feed the plants. This keeps the pond clean and almost weed free. Lower lake water is usually warm and rich in nutrients. It supports a large number of microscopic plankton, making the water appear cloudy.

Salt and soda lakes

Lake water contains saline minerals that are carried away by streams. Generally, minerals are transported from lakes to oceans. However, in hot climates, water evaporates as the lake fills up. As water evaporates, it leaves behind minerals, where it forms crystals on rocks and makes water very salty. As a result, salt or soda ponds are formed depending on the minerals.

Salt lake:- The Dead Sea water in the Jordan Rift Valley is so salty that no plants or animals can live in it.

Lake evolution

Nutrient-rich lowland ponds support a wide range of plant life, including plants such as reeds that grow along the edges of muddy ponds. The reeds are trapped in a mud trap, which is formed to allow more seedlings to take root. Over time, this process transforms the lake into an aquatic marshland. The trees take root and the swamp becomes a wet forest. Eventually the lake may disappear completely.

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